<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>选择器</title>
    <style>
        /* 类选择器 */
        .red{
            color:red
        }
        .size{
            font-size: 90px
        }
        /* 标签选择器，会让同种标签全部都使用该属性 */
        p{
            color: aquamarine;
        }
    </style>
</head>
<body>
    <p>111111</p>
    <p>1321312321</p>
    <div class="red size">2222222</div>
</body>
</html>